<wfs:GetFeature service="WFS" version="2.0.0"
  xmlns:st="http://www.stations.org/1.0"
  xmlns:wfs="http://www.opengis.net/wfs/2.0"
  xmlns:fes="http://www.opengis.net/fes/2.0"
  xmlns:gml="http://www.opengis.net/gml/3.2">
  <wfs:Query typeNames="st:Station" srsName="EPSG:4326">
    <fes:Filter>
      <fes:PropertyIsLike wildCard="*" singleChar="." escapeChar="\">
        <fes:ValueReference>st:Station/st:observation/st:Observation/st:description</fes:ValueReference>
        <fes:Literal>*sky*</fes:Literal>
      </fes:PropertyIsLike>
    </fes:Filter>
  </wfs:Query>
</wfs:GetFeature>